Maricopa County’s medical examiner ruled “complication of renal failure” as his cause of death, listing environmental heat exposure as a contributing cause. His swamp cooler had recently broken, his sister said. The house never had air-conditioning, though he did have fans.

In a family of “nerds and eggheads,” Sharon believed her brother had the most brilliant mind.

“He was the smartest person I’ve ever met in my life,” she said.

Stephen was an engineer. He was born in Moberly, Missouri, and the family made its way to Phoenix when he was 6. One Christmas he helped his mother, Maudie, type up a book about her life growing up on a farm in Moberly.

He dreamed of being a writer. His blog, Stephen’s Thoughts, includes the story his mother wrote about Moberly. He also wrote fantastical science fiction, stories with titles like “The Pomeranian and the Crawfish” and “Zombie dinosaurs!”

Toward the end of his life, Stephen’s health flagged. He had edema in his legs, Sharon said. The day before police officers found him dead, his doctor tried to contact him because lab results suggested he was in renal failure. The doctor requested a welfare check the next day.

Sharon found her brother’s journal after his death.

“He thought he could just tough it out,” she said. “He didn’t know he was dying.”

Stephen was honorable, she said, always the guy to put anyone else’s needs over his own.